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See detailXérogels de carbone à base de résorcinol-formaldéhyde en tant que matériaux d’anode pour batterie Li-ion; Synthèse et broyage avec contrôle de la granulométrie
Piedboeuf, Marie-Laure ULg; Léonard, Alexandre ULg; Pirard, Jean-Paul ULg et al

Conference (2013, May)

Xérogels de carbone à base de résorcinol-formaldéhyde en tant que matériaux d’anode pour batteries Li-ion : synthèse et broyage avec contrôle de la granulométrie Les xérogels de carbone sont des candidats ... [more ▼]

Xérogels de carbone à base de résorcinol-formaldéhyde en tant que matériaux d’anode pour batteries Li-ion : synthèse et broyage avec contrôle de la granulométrie Les xérogels de carbone sont des candidats prometteurs en tant que matériaux d’anodes de batterie Li-ion étant donné que leur faible variation de volume lors des cycles de charge-décharge devrait conduire à une durée de vie plus élevée. Néanmoins, du fait de leur morphologie fort différente de celle du graphite, tout un travail de mise au point du dépôt sur collecteur de courant se doit d’être effectué. Une partie de cette étude consiste à contrôler la granulométrie des particules issues du processus de broyage préalable à la préparation d’une encre. Dans ce travail, quatre xérogels de carbone de textures différentes ont été synthétisés et deux méthodes de broyage ont été utilisées pour réduire la taille des monolithes obtenus après synthèse. Les premiers résultats indiquent que la méthode de broyage n’a pas d’influence sur la distribution de la taille des particules et la structure des matériaux est bien conservée pour des particules de taille allant jusqu’au micromètre. [less ▲]

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See detailThe multiple SEA method: a method to synthesize Pt/carbon xerogel catalysts for Proton Exchange Membrane Fuel Cells (PEMFC)
Zubiaur, Anthony ULg; Chatenet, Marian; Maillard, Frédéric et al

Poster (2013, April)

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See detailEffect of current flow on bipolar plate/gas diffusion layer interfacial contact resistance in Proton Exchange Membrane fuel cells (PEMFC)
Stergiopoulos, Vaios ULg; Lafort, Adeline; Maseri, Fabrizio et al

in Proceedings of the Fundamentals and Development of Fuel cells 2013 conference (2013, April)

Stainless steel bipolar plates can be excellent alternative to graphite bipolar plates since they display better mechanical properties and the manufacturing procedure is easier and cheaper. However, they ... [more ▼]

Stainless steel bipolar plates can be excellent alternative to graphite bipolar plates since they display better mechanical properties and the manufacturing procedure is easier and cheaper. However, they are chemically instable in the corrosive environment of PEMFCs, and a thin oxide layer is developed on the plate’s surface. This layer causes a significant increase in the interfacial contact resistance (ICR) between the plates and gas diffusion layers. In an effort to characterize various stainless steel samples, before and after their exposure to the corrosive environment of a PEMFC, the interfacial contact resistance (ICR) between the plates and a commercial gas diffusion layer (GDL) was studied as a function of the pressure applied on the assembly. The ICR was studied in the range of 0-500 N/cm2 of pressure applied to the assembly; the ICR value was determined by means of galvanostatic potentiometry, where a constant current is applied to the assembly and the average value of the potential over time is recorded. The ICR is then calculated, after appropriate simplifications, as: ICR = Rtot = Iapplied / Vmonitored (1) It was observed that, besides the expected exponential reduction of ICR versus pressure, the value of the current applied to the assembly impacted greatly the obtained values for the ICR, irrespective of the applied pressure. This indicates that the observed phenomenon is not caused by any morphological changes on the interface. A possible explanation is that, at higher currents, the temperature increases locally due to ohmic heating, inducing thus changes in the GDL’s resistivity. [less ▲]

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See detailLa pile à combustible: du marché de niche au marché de masse
Job, Nathalie ULg

Conference given outside the academic context (2013)

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See detailPiles à combustible: vers une solution économiquement viable
Job, Nathalie ULg

Conference given outside the academic context (2013)

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See detailÉtude du mécanisme d'électrooxydation de BH4- sur platine à bas potentiel
Olu, Pierre-Yves; Rouhet, Marlène; Bonnefont, Antoine et al

Conference (2013)

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See detailApproaches to synthesize carbon-supported platinum-based electrocatalysts for proton-exchange membrane fuel cells
Maillard, Frédéric; Job, Nathalie ULg; Chatenet, Marian

in Suib, Steven (Ed.) New and future developments in catalysis. Batteries, hydrogen storage and fuel cells (2013)

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See detailBasics of PEMFC including the use of carbon-supported nanoparticles
Chatenet, Marian; Job, Nathalie ULg; Maillard, Frédéric

in Suib, Steven (Ed.) New and future developments in catalysis. Catalysis by nanoparticles. (2013)

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See detailEfficient Pt/carbon electrocatalysts for Proton Exchange Membrane fuel cells: avoid chloride-based Pt salts !
Job, Nathalie ULg; Chatenet, Marian; Berthon-Fabry, Sandrine et al

in Journal of Power Sources (2013), 240

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See detailCatalytic layer for PEMFC based on carbon xerogels
Deschamps, Fabien ULg; Traina, Karl; Pirard, Jean-Paul ULg et al

in Proceedings of the Fundamentals and Development of Fuel cells 2013 conference (2013)

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See detailMass transport in carbon gels with tuned porosity
Job, Nathalie ULg

in Spanish Carbon Group Bulletin (2012)

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See detailPropriétés physicochimiques et électrochimiques de catalyseurs Pt/xérogel de carbone synthétisés par la méthode de SEA multiple.
Zubiaur, Anthony ULg; Chatenet, M.; Maillard, F. et al

Conference (2012, October 01)

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See detailFonctionnalisation surfacique de poudre de carbone pour greffer des nanoparticules métalliques par plasma.
Laurent-Brocq, M.; Job, Nathalie ULg; Pireaux, J.-J.

Conference (2012, October 01)

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See detailPréparation de couches catalytiques pour PEMFC à partir de xérogels de carbone.
Deschamps, Fabien ULg; Traina, Karl; Pirard, Jean-Paul et al

Conference (2012, October 01)

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See detailAdsorption du bleu de méthylène sur des xérogels de carbone activés
Páez Martínez, Carlos ULg; Contreras, Soledad; Léonard, Angélique ULg et al

Poster (2012, October)

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See detailResorcinol-formaldehyde carbon xerogels as lithium-ion battery anode materials: influence of porosity on capacity and cycling behaviour
Piedboeuf, Marie-Laure ULg; Léonard, Alexandre ULg; Khomenko, Volodymyr et al

Poster (2012, July 05)

Carbon xerogels are promising candidates in the development of new high performance C-based anode materials for Li-ion batteries. Indeed, their specific capacities widely exceed that of conventional ... [more ▼]

Carbon xerogels are promising candidates in the development of new high performance C-based anode materials for Li-ion batteries. Indeed, their specific capacities widely exceed that of conventional graphitic structures, and they can be intercalated/deintercalated in a low-cost electrolyte based on propylene carbonate (PC), which has an excellent conductivity at low temperatures. In addition, such carbonaceous materials show very small changes of volume during the charge/discharge, providing a long cycle life of such an anode. Nevertheless, hard carbons also exhibit quite high irreversible capacity losses due to their intrinsic high microporosity and, compared to graphite, a poor rate performance related to slow diffusion of Li in the internal structure[1]. To reduce these disadvantages, the structural and textural characteristics need to be carefully controlled. Porous carbon xerogels can easily be prepared from resorcinol-formaldehyde aqueous mixtures, which are polymerized, dried and pyrolysed. The porosity of these xerogels is mainly governed by the pH of the precursor solution as well as by the drying procedure. Globally, these materials are composed of microporous nodules delimiting meso- or macroporous voids, the size of which is adjusted via the synthesis pH. Too a high microporosity can induce considerable irreversible capacity losses and too small mesopores may hinder the proper chemical diffusion of lithium ions within a bulk electrode material. The latter is often a rate-limiting step and optimized transport pathways could be provided by creating large mesopores or even macropores within the microporous carbon [3]. Here we report on the preliminary electrochemical characterization of porous carbon xerogels prepared by vacuum drying procedure. By adjusting the pH of the precursor solution, the materials obtained develop low to high values of specific surface areas and exhibit homogeneous pore sizes that range from several microns to several nanometers. The electrochemical performance of these materials as electrode compounds was tested by galvanostatic charge-discharge of 16-mm disc electrodes assembled in CR2016 coin cells or of 13-mm disc electrodes in home-made Swagelok-type cells. The first results show that all the samples show quite a high irreversible capacity during the first cycle; this irreversible capacity is proportional to the specific surface area. Its value nevertheless remains quite low for the low-surface area macroporous sample. The latter also shows the best reversible capacity after the second cycle, with values approaching that of commonly used graphite. For example, when cycled at a rate of C/20 for 10 cycles, this sample showed a capacity of 320 mAh/g; the value was kept at 200 mAh/g when increasing the rate up to C/5. The long-term cycling performance was investigated by cycling the anodes at C/20 and C/5. Again, the macroporous sample behaves best, with superior capacity retention and invariable discharge capacity of ~175 mAh/g after more than 100 cycles. The electrochemical properties of carbon xerogels was evaluated in the conditions which are used typically for graphite (cycles in the potentials range from 0.003 to 1.5 V vs. Li+/Li). A higher reversible capacity of 400 mAh/g could be obtained for the macroporous sample using a discharge with plating of Li as described in [4], but this method could not be accepted in the case of Lithium-ion batteries. These first results show that carbon xerogels are very promising candidates as anode materials for Li batteries, providing the textural characteristics are carefully controlled. The ongoing work is dealing with the establishment of possible relationships between textural features and electrochemical performance in order to shed light on the requirements that will dictate the best synthesis procedures. References: [1] T. Tran, B. Yebka, X. Song, G. Nazri, K. Kinoshita and D. Curtis, J. Power Sources, 85, 269, 2000. [2] N. Job, A. Théry, R. Pirard, J. Marien, L. Kocon, J.-N. Rouzaud, F. Béguin and J.-P. Pirard, Carbon 43, 2481, 2005. [3] F. Cheng, Z. Tao, J. Liang, and J. Chen, Chem. Mater., 20, 667, 2008. [4] W. Xing, J. S. Xue, J.R. Dahn, J. Electrochem. Soc, 143, 3046, 1996. [less ▲]

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See detailSynthesis and characterization of porous carbon xerogels and ordered mesoporous carbons for anode materials in Li-based batteries
Léonard, Alexandre ULg; Pirard, Jean-Paul ULg; Job, Nathalie ULg

in Fagadar-Cosma, Eugenia (Ed.) Insights into novel solid materials, their recyclability and integration into Li polymer batteries for EVs. Future research directions in this field.:Book of abstracts (2012, July 04)

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